Hyaluronic acid injections are used to treat osteoarthritis of the knee. This treatment is called viscosupplementation. The gel-like substance is administered with one to five injections (depending on the product) into the osteoarthritic joint. The most common site of injection is the knee, although it has been used and is being tested in other joints as well. There are multiple preparations including – but not limited to – Synvisc, Orthovisc, Hyalogen, Supartz, and Euflexxa. It takes up to two months to see the full effect of the treatment. These injections can be repeated as early as every six months.
A number of clinical reports have demonstrated these knee gel injections as an effective therapy for osteoarthritis of the knee. The potential mechanisms of action include lubricant effects, anabolic effects, chondral protective effects, and anti-inflammatory effects.
Side effects can include minor local reaction at the injection site. Rarely, acute swelling can occur, which must be evaluated for possible infection.